From 5aca118dbb0e07b7cfa4a17e9f595f7adbfa7fc3 Mon Sep 17 00:00:00 2001
From: Cuong Manh Le <cuong@windscribe.com>
Date: Mon, 27 May 2024 15:40:25 +0700
Subject: [PATCH] all: always reset DNS before initializing OS resolver

So ctrld could always get the correct nameservers used by system to be
used for its OS resolver.
---
 cmd/cli/cli.go  | 13 ++++++++-----
 cmd/cli/prog.go |  4 +++-
 resolver.go     | 16 +++++++++++-----
 3 files changed, 22 insertions(+), 11 deletions(-)

diff --git a/cmd/cli/cli.go b/cmd/cli/cli.go
index f4018c4..bdae37a 100644
--- a/cmd/cli/cli.go
+++ b/cmd/cli/cli.go
@@ -182,7 +182,7 @@ func initCLI() {
 				return
 			}
 
-			status, err := s.Status()
+			status, _ := s.Status()
 			isCtrldRunning := status == service.StatusRunning
 
 			// If pin code was set, do not allow running start command.
@@ -500,7 +500,6 @@ func initCLI() {
 			iface = runningIface(s)
 			tasks := []task{
 				{s.Stop, false},
-				{func() error { resetDnsNoLog(p); return nil }, false},
 				{s.Start, true},
 			}
 			if doTasks(tasks) {
@@ -509,10 +508,12 @@ func initCLI() {
 					mainLog.Load().Warn().Err(err).Msg("Service was restarted, but could not ping the control server")
 					return
 				}
-				if cc := newSocketControlClient(s, dir); cc == nil {
+				cc := newSocketControlClient(s, dir)
+				if cc == nil {
 					mainLog.Load().Notice().Msg("Service was not restarted")
 					os.Exit(1)
 				}
+				_, _ = cc.post(ifacePath, nil)
 				mainLog.Load().Notice().Msg("Service restarted")
 			}
 		},
@@ -927,13 +928,15 @@ NOTE: Uninstalling will set DNS to values provided by DHCP.`,
 					return true
 				}
 				tasks := []task{
-					resetDnsTask(p, s),
 					{s.Stop, false},
 					{s.Start, false},
 				}
 				if doTasks(tasks) {
 					if dir, err := socketDir(); err == nil {
-						return newSocketControlClient(s, dir) != nil
+						if cc := newSocketControlClient(s, dir); cc != nil {
+							_, _ = cc.post(ifacePath, nil)
+							return true
+						}
 					}
 				}
 				return false
diff --git a/cmd/cli/prog.go b/cmd/cli/prog.go
index 8dd83b5..8e35575 100644
--- a/cmd/cli/prog.go
+++ b/cmd/cli/prog.go
@@ -206,8 +206,10 @@ func (p *prog) preRun() {
 }
 
 func (p *prog) postRun() {
-	mainLog.Load().Debug().Msgf("initialized OS resolver with nameservers: %v", ctrld.OsNameservers)
 	if !service.Interactive() {
+		p.resetDNS()
+		ns := ctrld.InitializeOsResolver()
+		mainLog.Load().Debug().Msgf("initialized OS resolver with nameservers: %v", ns)
 		p.setDNS()
 	}
 }
diff --git a/resolver.go b/resolver.go
index bfb3394..49ac652 100644
--- a/resolver.go
+++ b/resolver.go
@@ -32,12 +32,8 @@ const (
 
 const bootstrapDNS = "76.76.2.22"
 
-// OsNameservers is the list of DNS nameservers used by OS resolver.
-// This reads OS settings at the time ctrld process starts.
-var OsNameservers = defaultNameservers()
-
 // or is the Resolver used for ResolverTypeOS.
-var or = &osResolver{nameservers: OsNameservers}
+var or = &osResolver{nameservers: defaultNameservers()}
 
 // defaultNameservers returns nameservers used by the OS.
 // If no nameservers can be found, ctrld bootstrap nameserver will be used.
@@ -49,6 +45,16 @@ func defaultNameservers() []string {
 	return ns
 }
 
+// InitializeOsResolver initializes OS resolver using the current system DNS settings.
+// It returns the nameservers that is going to be used by the OS resolver.
+//
+// It's the caller's responsibility to ensure the system DNS is in a clean state before
+// calling this function.
+func InitializeOsResolver() []string {
+	or.nameservers = defaultNameservers()
+	return or.nameservers
+}
+
 // Resolver is the interface that wraps the basic DNS operations.
 //
 // Resolve resolves the DNS query, return the result and the corresponding error.